Brent crude oil slipped below $109 to $108.58 at 5:50 GMT on Tuesday morning as investors put their faith in a meeting set to take place on Thursday between the US, the EU, Russia and Ukraine.

The commodity has been buoyed by worries that the crisis in Ukraine is leading to a military clash between Moscow and Kiev, but now most are hoping the issue can be resolved diplomatically when both sides sit down to talk on Thursday.

Over the weekend, pro-Russian demonstrators stepped up their protests and refused to vacate government buildings even after the Ukrainian government issued a serious warning.

The separatist groups have allegedly been tied to Russian special forces, which has driven the wedge between Moscow and the West even deeper.

Now, the US and the EU are considering adding to sanctions against Russia, but how and when to do so will likely be determined after Thursday's meeting. Policymakers from both regions are hoping a diplomatic solution will be found and no further sanctions will be needed.

According to Reuters, President Obama spoke with Russian President Vladimir Putin to warn him that his actions were exacerbating the problems in Ukraine and were counterproductive to finding a diplomatic solution.

He told Putin that the US was planning to ratchet up sanctions and squeeze Moscow further if the situation worsens.

Meanwhile, Libyan oil was slowly making its way back to the market as the nation's government regained control of several oilfields across the country.

After being occupied and shut down by rebel groups for eight months, the nation's export terminals are reopening and returning to capacity.

However, not all of Libya's oil ports have been returned to the state run National Oil Corp.

The eastern Zueitina oil port is still shut down despite a week old agreement which said it would be reopened.